Regional and Long-Term Analyses of Stable Isotopes of Fish and Invertebrates Show Evidence of the Closure of a Pulp Mill and the Influence of Additional Stressors
Bibliographic record
Abstract
Abstract A bleached kraft pulp mill discharging effluent to the Mattagami River in northern Ontario, Canada, closed after almost 90 yr of operation. During its operation, effluent from the mill influenced biota in the downstream areas. To assess shifts in the reliance of biota from mill-derived nutrients, the isotopic composition (δ13C and δ15N) of white sucker (Catostomus commersoni) muscle and whole mayflies (Hexagenia sp.) were compared before (1990s) and after the pulp mill's closure (2012–2014). To better understand other potential sources of spatial and temporal change, samples from 3 other tributaries in the basin with dams, ongoing pulp mill operations, sites receiving sewage, and at several reference sites were collected and compared. Irrespective of time period, biota collected at sites downstream of both dams and active pulp mills tended to have elevated δ13C values, but variable changes in δ15N (negligible in most cases) when compared with upstream samples. The isotopic composition of mayflies varied at reference sites over time, with decreasing values of δ13C and δ15N (mayflies only) with increasing depth, and there was evidence of lower δ13C in fish after the pulp mill closure. Overall, these results suggest the importance of long-term, regional-scale measurements for documenting the effects of stressors on nutrient use by aquatic species. Environ Toxicol Chem 2020;39:1207–1218. © 2020 SETAC
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".